Several devices and methods have been used in the past to collect, preserve, transport, dilute and discharge chemical, environmental or biomedical specimens, including in particular fecal samples for later analysis by a laboratory or for clinical studies. One problem with specimen contaminated with germs is in particular the hygienic component of collecting the samples and diluting them in an appropriate tube.
DE 10 2007 057 760 B3 discloses a device for collecting and dissolving a pastry sample. The sample pin of this device has a hollow end part for collecting the sample. The end part comprises further windows or openings in its side wall. When the sample in the sample pin is dissolved in a solution chamber, the end part of the chamber can be broken off and the dissolved sample can be discharged.
U.S. Pat. No. 7,048,693 B2, EP 1384442 B1 and US 2006/0210448 A1 show a specimen collection, storage and transport device with a sample pin for collecting the specimen. This sample pin has a handle and an elongated pin with a spiral-shaped end. This end is put into a sample to be probed, pulled out again and shoved into the corresponding tube. The tube is divided into two sections, an upper section and a lower section. The separation wall between these two sections comprises a hole through which the sample pin and in particular the spiral-shaped end is pushed and a certain amount of the collected sample can be brought into the second section. This second section is filled with a solution. By agitating the tube after the sample pin has been closed by screwing it into the tube via complementary threads, the sample is diluted in the solution.
To discharge such a diluted sample, for example to put a certain amount of the diluted sample on an analytical test strip or a test plate or any other device, the discharge port comprises a breakable closure, which is opened by breaking off the tip of the discharge port. After that, the diluted sample can be discharged through the broken tip by pressing the body of the tube.
One problem is that the samples are not always of the same structure. That is, the samples can vary from a very liquid state to a very solid state. Thus, with the above-mentioned prior art tubes, or more particular with the sample pins used therewith, it is difficult to take a predetermined amount of a sample which is either very solid or very liquid. For example, in a very liquid sample the spiral-shaped end of the sample pin is not ideal of keeping the sample on the sample pin, because a liquid sample will drop off the sample pin.
Therefore, it is very difficult to get a predetermined amount of such a sample into the tube. There are also other solutions, like a spoon-shaped device or circumferential recesses at an end of a sample pin, as can be seen in various other documents.
However, with the circumferential recess the same problems occur as with the above-mentioned spiral-shaped pin according to the state of the art, whereas a spoon-shaped device makes it very difficult to get a specific amount of a sample, because the sample will adhere at the bottom of the spoon and this bottom cannot be scraped off by a through-hole as can the sample pins of the above-mentioned prior art.
A further disadvantage of the prior art is that discharging of the diluted sample via the breakable closure is difficult to control. By or after opening the discharge port it may happen that pressure is brought onto the tube and some of the diluted sample is discharged by accident. Finally, once opened, the types of prior art tubes cannot be closed again and, thus, it is very difficult or impossible to store them and use again for a second test and the like.
Another problem occurs when the diluted sample should be transferred into another tube for further processing, i.e. mixing the already diluted sample with the same or another solution for further diluting (some medical utilizations need highly diluted samples and/or a dilution buffer different from the first buffer or liquid). For this purpose, a pipette is generally used to transfer a predetermined volume of the diluted sample contained in the tube. Thus, the tube has to be opened and the pipette has to be inserted into the tube. However, this is a possible source for contamination of the sample and also hygienically not free of risks. Therefore, the above mentioned devices are even not suitable for near patient testing. Moreover, if the sample has to be further processed, home testing by a patient is impossible with these tubes, because the danger of contaminating the test sample with foreign particles as well as contamination of the environment and the user himself with the test sample is simply too high by untrained persons using a pipette.